How to Seal Polyurethane

SealWerks is a leading manufacturing company and expert of sealing polyurethanes together. We can fabricate a wide assortment of customized sewn industrial fabric and RF welded vinyl products. We provide radio frequency (RF) welding services for various thicknesses of vinyl materials to make custom shapes, combine vinyl seams and to create a seal between two materials to create the product you want.

Radio frequency (RF) welding is utilized to weld polyurethane to itself to form a seal. Polyurethane is a plastic material and can be fabricated by joining urethane groups with the polymer units. The material is resilient and durable; this type of material exists in flexible foams, films, and chemical-resistant coatings.

Polyurethane is used to make a wide variety of products which include; IV bags, blood bags, colostomy bags, pressure cuffs, glucose bags, saline bags, protective covers, insulation blankets, acoustical blankets, air bladders, air curtains, backdrops, baffles, bags, and more!


Process of Radio Frequency (RF) Welding and Polyurethane Sealing

RF welding is also known as Dielectric welding or High Frequency (HF) welding, which means it is a method of joining thin sheets of polar thermoplastic material together. RF welding uses high frequency (13 to 100 MHz) electromagnetic energy to fuse the materials together.

The material is placed on the table and the sealing process of the two materials is directed by dies as the upper platen comes down, squeezing them together. The sealing takes place when radio frequency waves are sent through the small area between the table and die, that is occupied by the materials to be fused together.

The radio frequency (typically 27.12 MHz) will excite the molecules, making them move faster, which then creates heat. The internal heat will end up melting the polyurethane to seal the material together. Additionally, high frequency, or dielectric sealing, is the process of heating the material from within, which can be localized using tooling.

The result of the process is a seamless area made of a stronger bond than the original material. Once the welding has been completed, SealWerks can finish your welded product with any of our additional in-house services, which include Hot Air welding, sewing, and die cutting services.

Welding polyurethane with another material, like vinyl, is a process that must be checked for compatibility. The most common materials used for RF sealing are polyurethane and PVC while other polymers like Nylon, EVA, PET, and some ABS plastics can be welded using this process.

The result is a product that will contain a substance within the material or that the product will keep unwanted substances out. No matter what it is you require in a welded polyurethane product, SealWerks is an industry leader for commercial sewing and radio frequency welding services. We streamline the “concept to product” process. We will combine your ideas with the absolute best innovative technology to create a product that will exceed your expectations.

Polyurethane Facts

  • Polyurethane is reaction based and a bond is produced when in the presence of a catalyst or UV light; a co-mingling of molecules forms the bond.
  • Polyurethane has a long tail – the molecular structure which allows it to bond very well.
  • The range of thickness of polyurethane film is .001” to .120.”
  • The range of durometer on the most common shore A scale is 40-95.
  • Ether, Ester, Thermoplastic Urethane (TPU) and Thermoplastic Elastomer (TPE) are types of polyurethane.
  • High Elastomeric Factor – 200% – 600%.
  • Fairly-high tolerance to heat.
  • Fairly-high tolerance to abrasion.
  • PU and PVC are polar molecularly structured.

Advantages of Radio Frequency Welding Polyurethane Material:

  • Material is strengthened at the Seal.
  • Seal is Fluid Proof.
  • Greater Shear Tear-Resistance.
  • Non-Wicking Seams.
  • Almost Invisible Seam.

Contact us today to discuss your radio frequency welding and heat sealing needs.